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Many other organisms have been tested for the biological control of vectors.
Candidates for controlling larvae of Ae. aegypti and other mosquitoes that
develop in small containers are dragonfly larvae in Myanmar, the copepod
crustacean Mesocyclops aspericornis in French Polynesia (Rivière et al. 1989),
and the predatory mosquito species, Toxorhynchitis (WHO 1988).
Trapping
Mechanical and other types of traps have been used to reduce populations of
tsetse flies. Several designs have been developed, some of them incorporating
chemical attractants and insecticides. In Uganda, an effective tsetse trap has
been made from old tires and locally available plant materials (Okoth 1986).
Light traps, installed in pig sties, have been tested for the control of Culex
tritaeniorhynchus in Japan (Wada 1988).
Environmental management
Changing the environment to prevent vector breeding or to minimize contact
between vectors and people can be an effective control mechanism (WHO
1982). Environmental management methods (Birley 1989) include:
i Environmental modification, i.e., any permanent or long-lasting change
in land, water, or vegetation, such as filling, draining, or forest clearance;
Environmental manipulation, e.g., flushing streams, changing water
salinity, and removing shade plants; and
Modifying human habitation or behaviour, e.g., locating new settlements
away from vector populations, modifying house design, and
changing water supply and waste disposal.
Intermittent irrigation was used to prevent the development of mosquito
larvae in rice fields (Lacey and Lacey 1990) and layers of expanded polystyrene
beads prevented Culex quinquefasciatus from laying their eggs in wet pit
latrines in Tanzania (Maxwell et al. 1990). Much environmental management
work can be done by community volunteers with guidance in the initial stages
from vector-control specialists.
Training and education
Integrated control strategies require more people trained in vector biology. In
addition to the usual sources of health education, such as schools and clinics,
information can reach the public through billboards, newspapers, radio, and
television. A dengue-control theme has even been incorporated into a "soap
opera" in Puerto Rico (Gubler 1989).
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